Approach 1
When we using SMTP of MS office 365 and we are getting error like below then we need to configure and change setting in Office 365 manage panel. And also need to check Credentials password of associated user account password is expired or account is locked. And also set "Never Expire Password" option office365 exchange account.
Approach 2
Login into office 365 account and go to Admin menu and click on Exchange.
After that go to "recipient" > "mailboxes"
Under "mailboxes" > click on "Edit" icon and open a popup.
Inside the popup click on "mailbox delegation"
Remove display name "NT AUTHORITY\SELF" and Add new display user name click on save button.